Thesis (PhD (Biochemistry))--Stellenbosch University, 2008. / This study describes: • the cloning and sequencing of cytochrome P450 17 -hydroxylase/17,20 lyase (CYP17), 3 -hydroxysteroid dehydrogenase (3 HSD) and cytochrome b5 from the South African Angora goat; • the identification of two CYP17 genes encoding two unique CYP17 isoforms in the Angora goat; • the development of a UPLC-APCI-LC method for the separation and quantification of seven adrenal steroids; • the characterisation of the enzymatic activity of the two Angora CYP17 isoforms expressed in non-steroidogenic COS-1 cells. The Km and Vvalues for the metabolism of pregnenolone and progesterone were determined; • the development of a rapid and accurate real-time PCR genotyping test for CYP17 in Angora goats. Three unique genotypes were identified; • the determination of blood cortisol levels upon the stimulation of the HPAaxis by intravenous insulin injection in the three Angora goat genotypes.